A page from the "Calendars" exhibit...

13 June 2018

The moon changes in appearance and location in the sky everyday, which is why we refer to the moon by its phases: new moon, new crescent moon, 1st quarter moon, waxing gibbous, full moon, waning gibbous, 3rd quarter, and old crescent. See how the phases change over the course of the moon’s 29.53-day cycle.

Step outside! Keep track of the moon in your night sky, and chart the changes yourself. See our tips on how to chart the moon in the sky and explore the phases of the moon over the course of its 29.53-day cycle. In the process, you’ll discover why lunar months aren’t an exact match with calendar months.